Vol. 12 No. 7 (2014)

The use of seeds from immediate previous crop as a seed source for planting soybean is a common practice used by farmers in the Mekong delta. This study was conducted to determine the best time for early-harvesting of MTĐ517-8 soybean seeds for sowing in the next season. Two experiments were conducted (1) to determine the effect of harvesting time on the rate of the germination and seedling quality and (2) to study the effect of harvesting time on the yield. The first experiment was set up using a completely randomized design (CRD) with 5 treatments (20, 15, 10 and 5 days prior to full maturity and mature seeds R8 (control) and 5 replications. The results showed that the rate of germination, root length and root diameter of seeds harvested at day 20 before full seed maturity were not significantly different compared with the control. Six days after sowing, the weight, height and diameter of seedlings from all the treatments were not significantly different with the control. The second experiment was carried out using a CRD with 5 treatments with 5 replications. The results indicated that the height of plants grown from seeds harvested 20 days before full maturity was not significantly different with seeds harvested at maturity. Moreover, the yield components, grain yield and harvest index were not significantly different among all the treatments and control. The study confirms that soybean seeds can be harvested as earlier as 20 days before full seed maturation for the next season seeds.             

This paper presented the evaluation of late blight resistance of somatic hybrid potato plants generated via protoplast fusion between Solanum tuberosum varieties (Delikat, Rasant, Agave, Atlantic) with wild potato species (S. bulbocastanum, S. pinatisectum, S. Tarnii). Late blight resistance was evaluated using detached-leaf method, tuber slice test and field test. The results revealed that only somatic hybrid plants between S. bulbocastanum with cultivated potato variety Delikat showed resistance against late blight disease. Molecular marker analysis for Rpi-blb, resistant-related genes, found the presence of Rpi-blb1 and Rpi-blb3 genes in S. bulbocastanum and its somatic hybrids. This confirmed that late blight resistant genes were successfully transferred from wild potato to cultivated potato via protoplast fusion.

Somatic embryogenesis is a process where a plant or embryo is derived from a single somatic cell or group of somatic cells. When compared to other methods of vegetative propagation, somatic embryogenesis has more applications, such as clonal propagation of genetically uniform plant material, elimination of viruses,  provision of source tissue for genetic transformation, generation of whole plants from single cells and development of synthetic seed technology. The aim of this study was to establish an in vitro system for the induction of somatic embryo in Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.) – a precious and economic medical herb of Vietnam. Leaf explants of 0.5 x 0.5 cm in size were cultured on Murashige and Skoog (MS) medium supplemented with 1.0 mg.l-12,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg.l-1 naphthaleneacetic acid (NAA) for callus induction. Callus explants were cultured on MS medium supplemented with various concentrations of 2,4-D, kinetin and NAA to establish embryogenic culture. After 8 weeks of culture, globular structures were obtained. The highest efficiency of somatic embryo production was achieved on MS medium supplemented with 1.0 mg.l-1 2,4-D, 0.2 mg.l-1 kinetin and 0.5 mg.l-1 NAA. After 12 weeks of culture, all stages of somatic embryogenesis, including globular, heart-, torpedo- and cotyledonary-shaped embryos were observed in embryogenic clusters. Histological observation and scanning electron microscopy (SEM) analysis revealed that the embryos had bipolar structure.

A total of six dehydrin (DHN) genes have been found in the whole genome of Clementine (Citrus clementina). This work aimed to study the characteristics and structure of DHN in this species. All of six DHN proteins were highly hydrophilic. Their high aliphatic index suggested that clementine DHN might be thermostable proteins. Only two KS-type genes, CclDHN1 and CclDHN6, had no intron. Therefore, four others were discontinuous coding genes with an intron which separates two exons within the S fragment. The predicted 3D modeling structure showed many amphipathic α-helices in the secondary structure of DHN proteins. In addition, the serine phosphorylation sites also were predicted in the S fragment region. Two clementine DHN genes, CclDHN1 and CclDHN2, expressed in many different tissues under various environmental conditions .

Protocorm-like bodies (PLBs) were formed from apical meristem culture of four Cymbidium species on MS medium supplemented with 0.5 mg/l αNAA., 1 mg/l BA after 45 days under light condition. PLB longitudinal thin cell layer culture was used as a technique for PLBs micropropagation on MS medium containing 0.5 mg/l αNAA, 1 mg/l BA, 10% coconut water (v/v), 30 g/l sucrose, 0.2 g/l glutamine, 1 g/l activated charcoal and 8 g/l agar. These collected PLBs were maintained and proliferated on the same medium after 2 months and then transferred to MS medium supplemented with 0.5 mg/l αNAA, 1 g/l activated charcoal, 30 g/l sucrose, 10% coconut water (v/v) and 8 g/l agar for plantlet regeneration. Histological observation proved that these PLBs originated from somatic embryos. Plantlets regenerated on medium without plant growth regulators after 4 months resulted in well-developed shoots and roots. This investigation is important for micropropagation and preservation of the high-economic Cymbidiums.

This study aimed to examine initial protocol of micropropagation for angel flower (Angelonia goyazenzsis Benth). Young leaves were cultured on MS medium supplemented with 0.2 mg/l NAA and  BA at different concentrations for shoot induction. The most effective rate of adventitious shoot proliferation was induced on MS medium supplemented with 1.5 mg/l BA while MS medium supplemented with 0.1 mg/l IBA was suitable for in vitro  rooting stage. In vitro derived plantlets were successfully established in the substrate with combination of sand: smoked rice husk in the ratio of 1:1. These results provide the basis for further studies on large-scale rapid propagation of angle flower. 

A study on physiological and biochemical changes of germinating seeds and seedlings of two soybean varieties DT2008 and DT84 in low temperature conditions (80C, 120C, 160C and 250C as control) were carried out. The germinating seeds and seedlings were grown in Microclima chamber AXYOS E800 and the parameters were measured by the automatical devices connected to computers. The results showed that germination rate, chlorophyll fluorescence performance and photosynthetic intensity reduced markedly under the influence of low temperatures, while proline and glycine betaine content in sprouts and leaves increased dramatically. The ìnfluence of low temperatures expressed most clearly when the temperature lowered down to 80C and in the early days of the experiment.

Lily can be propagated by various vegetative methods namely by offsets, stem bulblets, stem bulbils, bulb scales or tissue culture cells. Among these methods, the propagation by bulb scales is mainly used in the countries producing lily bulbs. In Vietnam, this propagation method has not jet put into place. Moreover, techniques in producing lily bulbs with cold treatment to break the dormancy of commercial lily bulbs have not been fully studied under Vietnam conditions. This study aimed to identify optimal temperature and time for dormancy breaking of commercial lily bulbs and to examine morphological change and biochemical chages of reserve compound during vernalization process. Results indicated that cold treatment quickly reduced starch and sugar content in bulbs towards increase in soluble sugars and saccharose until 7 weeks of treatment. It was found that temperature of 2oC and a duration of 7 weeks were optimal for vernalization of commercial Belladonna bulbs in terms of sprouting rate (98,5%). The results provided a basis for further research in the production of lily bulbs by the bulb scale method.

Increased drought in many parts of the world is a major cause of promoting the projects and researches to develop drought-resistant crops with high productivity. A great deal of researches focused on identifying morphological characteristics, biochemical and physiological parameters. Besides, studies on the nature of drought tolerance at the molecular level have been scientists’ interest. Drought tolerance of 25 local upland rice varieties at the seedling stage was identified, wherein Giang Bau was found to show the best drought tolerance variety while Khau lay khao exhibited lowest degree of drought tolerance. The use of RAPD marker with 20 random primers revealed genetic relationship of 25 local upland rice varieties with the coefficients of similarity among upland rice cultivars ranging from 79% to 92%. LTP coding genes of two local upland rice varieties with different drought resistance was isolated and identified. The comparison and analysis of LTP gene sequences among two local upland rice varieties (Giang bau and Khau lay khao) and a Japanese rice variety (Yukihikari) showed that the genetic similarity of LTP gene sequences between Yukihikari and Giang bau is 100% and the genetic similarity of LTP gene sequences between Giang bau and Khau lay khao is 98.1%. Comparing amino acid sequences of LTP proteins among these three varieties showed an increase of amino acid valine residue in Khau lay khao’s LTP protein and an increase of the amino acid leucine residue in Giang bau’s LTP protein.

This paper presented results of induction and multiplication of somatic embryos of Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.) in liquid media. Leaf explants of in vivo plants were cultured on MS agar medium supplemented with 1 mg/l 2,4-D + 0.2 mg/l kinetin for the induction of friable calli. The friable calli were cultured in MS liquid medium supplemented with 1 mg/l 2,4-D + 0.2 mg/l kinetin + 500 mg/l casein hydrolysate for the formation of a cell suspension. This cell suspension was cultured in a B5 liquid medium with 3 mg/l IBA for the formation of a globular somatic embryo suspension. Embryonic cotyledon explants and intact immature somatic embryos from this suspension were cultured on MS agar medium containing 10% (v/v) coconut water with/without 0.2 mg/l IBA for the induction of secondary embryogenic calli and somatic embryos. These embryogenic calli and somatic embryos were also cultured in liquid media with or without plant growth regulators in conical flasks and in bioreactors. The results have laid the foundations for large-scale plant micropropagation and production of secondary metabolites.

Theo hướng nghiên cứu ảnh hưởng của nguyên tố vi lượng (NTVL) đến khả chống chịu của thực vật, chúng tôi tiến hành thí nghiệm nghiên cứu ảnh hưởng của NTVL molipđen (Mo) dưới dạng muối amon molipđat 0,03% đến các giống đậu tương ĐT22, ĐVN9, ĐT26, William82, ĐT2008 trong điều kiện hạn ở giai đoạn cây con. Kết quả nghiên cứu cho thấy, Mo có ảnh hưởng tích cực đến hàm lượng diệp lục của lá. Trong điều kiện hạn có bổ sung Mo, hàm lượng diệp lục tổng số của các giống đậu tương nghiên cứu cao hơn so với đối chứng từ 5,1 - 73,8% (3 ngày hạn). Một số cơ chế giúp cây đậu tương chống chịu với điều kiện hạn như: sự tăng hàm lượng prolin, tăng hàm lượng nước liên kết của lá, tăng chiều dài của rễ cây… khi cây được bón bổ sung Mo cũng là kết quả của nghiên cứu này. Hơn nữa, việc bổ sung NTVL Mo còn làm tăng năng suất cũng như phẩm chất hạt của các giống đậu tương nghiên cứu (hàm lượng nitơ protein của hạt cao hơn so với đối chứng từ 44,4 - 93,6%). Như vậy, molipđen có ảnh hưởng tích cực nhất đối với khả năng chịu hạn của hai giống chịu hạn kém hơn là ĐT22 và ĐT26. Kết quả nghiên cứu này là cơ sở khoa học để đưa ra các giải pháp nâng cao khả năng chịu hạn của các giống đậu tương chịu hạn kém được gieo trồng ở những vùng sinh thái khó khăn về nguồn nước tưới và cũng như đối với đậu tương trồng vụ hè.

Nannochloropsis oculata grown in modified f/2 medium exhibited a double sigmoid growth curve with four phases: two phases of rapid growth separated by an intermediate slow growth phase, and a saturated phase. In the rapid growth phases, microalgal cells divided rapidly and achieved 2x107 cells per mL on the sixth day. The slow growth phase occurred with the increase of cell diameter and dry weight. The last phase started from the twelfth day, in which there was little or no growth. Effects of sodium chloride on N. oculata cell division depended on concentration and time of treatment. The removal of sodium chloride (NaCl 0M) or the increase of sodium chloride (NaCl 2M) in ten hours from modified f/2 medium yielded in the increase in cell division. Besides, the extension of treatment time from ten to twenty hours resulted in decrease of sodium chloride effects.

The sugarcane variety VN84-4137 that was successfully confirmed with preliminary transformation experiments was further transformed with  Bt genes including a single synthetic gene cry1Ab and a hybrid synthetic gene cry1B-cry1Ab. After infection and co-culture with Agrobacterium, sugarcane calli were selected on callus induction medium with 3 mg/l phosphinothricin (PPT). Resistant calli were transferred to selective regeneration medium for shoot induction. Three cry1Ab lines and one cry1B-cry1Ab transgenic line were identified by PCR and Southern blot. Protein expression of Cry1Ab and Cry1B-Cry1Ab assayed by quick test kit gave positive results. Transgenic plants exhibited a normal phenotype.

Rhynchostylis gigantea (Lindley) Ridley is a beautiful flower preferred by the market and has the potential to expand production in Vietnam. The major drawback of growing Rhynchostylis gigantea in Northern Vietnam is attributed to slow growth and development of the plants. Each year, the plants form only 1-2 leaves and take 3-4 years from planting to flowering. To overcome limitations in the Rhynchostylis gigantea production, the plant growth and development in different ecological regions, relationship between leaf and root growth and some flower characteristics were studied. The results showed that the plants grew fast in Southern conditions, followed by the Red River Delta and slowest in the Northern mountainous region. There existed a loose correlation between leaf length and root length (R2= 0.2081), but close correlation between leaf length and flower stalk length and number of flowers (R2= 0.8236 and R2 = 0.8121, respectively). Application of exogenous GA3 at 150ppm on 1-year old plants increased plant growth and shortened the time from planting to flowering from 3 years to 2 years with flowering proportion of 47%. Application of GA3 concentration of 200ppm on 2-year old plants increased leaf length, flower stalk length and the number of flowers per florescence with flowering proportion reached 80%.

Jatropha curcas is used to produce biodiesel and to make a wide range of products in agriculture, pharmaceutical industry, environment protection…. Therefore,  Jatropha curcas receives more and more attention from many countries. In the present study, Jatropha curcas introduced from Thailand and India was planted on sandy soil in  Thua Thien Hue and evaluated for physiological and growth characteristics. The survival rate of two Jatropha varieties was 86-90%. Chlorophyll a content was 2.18-3.09 mg/g; chlorophyll(a+b)/carotenoid ratio was between 4.44-5.78. The content and proportion of photosynthesis pigments were characteristic of sun-loving plant group. The highest total carbon content of Jatropha varieties Thailand and India was 306.5 mg/dm2 and  228.3 mg/dm2, respectively, at light intensity 17,800 lux. After two years of planting, both introduced Jatropha varieties survived but exhibited slow growth due nutrient depletion and water deficit. It is, therefore, suggested that no investment be taken for Jatropha development on sandy soil of Thua Thien Hue because of poor adaptation, slow growth and low economic efficiency.

The organogenesis (shoots and roots) is a complicated process, influenced by various endogenous and exogenous factors. Therefore, to understand the formation of the initials, several techniques have been used as anatomy, inhibitors and plant growth regulators supplement. In this study, we investigated the effects of plant growth regulators on the callogenesis, shoot formation and the process of shoot morphogenesis of Cinnamomum camphora (L.) Sieb. The results showed that the WPM medium supplemented with 2% sucrose, 0.5 mg/l NAA and 0.2 mg/l BA was suitable for the callus formation. WPM medium supplemented with 2% sucrose and 1 mg/l BA was the excellent medium for shoot multiplication (the mean of 7.7 buds/explant and 5.57g fresh weight). Morphological anatomy of shoots showed that the cortex parenchyma cell is the position to initiate shoot formation.

In this study, six sesame varieties collected from several provinces were used to determine chemical composition. The indicators of the nutritional quality of sesame seeds, such as lipid content, biochemical indicators (acid indexes, iodine numbers, and soap indexes), mineral contents and fatty acid contents were analyzed for comparison between the different sesame varieties. The results showed that three varieties, V5, V14 and V17 have high nutritional value and quality (lipid content more than 50%; acid indexes less than 3). All six varieties have high contents of minerals and unsaturated fatty acids (>70% of oleic, linoleic, linolenic).

The present paper reported hypersensitive response (HR) in roots of soybean cultivar “Nam Dan”  exposed to Pb2+ ion with concentrations of 0.1, 0.5 and 1.0mM after 6 hours treatment. An increase in content of thiobarbituric acid reactive substances (TBARS)-products of lipid peroxidation, and the high percentage of membrane injury caused serious cellular damage in root cells. Hydrogen peroxide (H2O2) was strongly induced and soon reached high level, however, the burst of superoxide anion radical (O2.-) was not recorded. The enhancement of HR was not correlated with the treated concentrations of  Pb2+ . The activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) rapidly increased and maintained high level in 6-48 hours after t Pb2+ treatmen, making contribution to control the burst of H2O2 and O2.- in HR in soybean roots.

Effect of light sources and containers on rapid multiplication and growth of Dianthus variety Hong Hac in tissue culture were studied. The results showed that, the use of cylinder flask closed with a cotton plug and plastic bag ventilated with a filter membrane gave highest plant quality. In rapid multiplication phase, lamp type LED 17R-3B had highest effects on formation of leaf, shoots and plant quality when cultured in cylinder flask closed with both cotton plug and/or plastic bag ventilated with filter membrane.  LED 13R-4B-3W had positive effects on plant quality compared to other lamp types.

The present paper reported the results on the genetic transformation of two cherry tomato cultivars, TN412 (pureline) and TN TN48 (F1 hybrid) with the HBsAg for long-term objective of producing the plant edible vaccine against Hepatitis B virus.  Shoots regenerated from cotyledons served as materials for transformation experiments. The 7-day old cotyledons of tomato seedlings were infected and co-cultivated for 2 days with the Agrobacterium tumefaciens strain carrying the HBsAg gene [driven by the PDS (phytoene desaturase) and T7 promoters], kanamycin resistance gene nptII and gusA reporter gene. Two days after co-cultivation, the cotyledons were washed with  cefotaxime solution and cultured on the MS medium containing + 0.5 mg/l IAA + 2 mg/l BA + 500 mg/l cefotaxime and 30 - 50 mg/l kanamycin for selection of transformants. Through at least 04 rounds of selection (15 - 20 days/round), various kanamycin resistant (KR) lines were obtained in both cultivars and they were confirmed for the presence and expression of transgenes by the GUS assay, by the PCR and Southern blot and western blot analyses. Several T1 individuals from T0 line were evaluated for presence and expression of the nptII gene by the in vitro KR assay and by the PCR analysis. The presence of the HBsAg gene in the T1 individuals also was carried out by the PCR technique.  

This paper reported  the success of propagation via callus of dragon fruit and growth  of  in vitro derived plants in  nursery. MS medium supplemented with 0.5 mg/l BA was effective for shoot regeneration from callus while MS medium containing 0.5 mg/l NAA was suitable for root induction. Rooted plantlets were acclimatized successfully after one months transferred to green-house and grown in a 1:1 (v:v) soil to coir mixture. Vigorous plants were obtained after four months using 16:16:8 fertilizer  with watering 2 times per day.

This study examined the application of somatic embryogenesis and ex vitro stem cutting techniques for production of high quality and virus-free Piper nigrum planting materials. The results indicated that MS medium supplemented with 0.05 mg/l TDZ and 1.0 mg/l IBA was best for embryo induction with a rate of 73.2% and MS medium containing 3 mg/l BA gave the highest rate of shoot forrmation (66,7%) from leaf callus after 60 and 28 days of culture, respectively. Cuttings taken from ex vitro plants produced healthy root system when watered 6 times daily. Plants raised from these cuttings thrived best when misted 3 times a day.